Determination of the Precision of Quantitative Measurement Methods at Machakos County, Kenya.

Abstract

Introduction: Measurement precision is the consistency of indications obtained as a result of repeat measurements on similar or the same objects, it gives information related to the method’s reproducibility. Precision is a crucial aspect of the method verification process. The study aimed to determine the precision of the quantitative measurement methods in the Clinical Chemistry laboratory through a systematic review and meta-analysis at Machakos County, Kenya. Methods: Internal quality control material (IQC) and pooled patientserum samples were used to measure precision. The IQC material and pooled serum samples both met the criteria for pathological and normal values.A purposive sampling technique was used, where Roche Cobas® Integra 400 Clinical Chemistry analyser was used to perform a comparative descriptive analysis, following guidance by the Clinical Laboratory Improvements Amendment 1988 (CLIA) and the Clinical Laboratory Standards Institute (CLSI). Data analysis was carried out using Excel Windows 10 MS Office 2021.The coefficient of Variation (CV) % was calculated from the obtained results mean and standard deviation and compared to manufacturers’ CV % and published CV %. Results: Short-term precision -All analytes’ control levels except Chloride (PCC1) met CLIA target coefficient of variation (CV) %. Fifteen (15)analyte levels met the manufacturer’srecommended CV %, and eleven (11) failed. Long-term precision – Ten (10) analytes for both control levels passed the target CLIA CV %. Three analytes (Chloride, Potassium and Urea)both control levels failed to achieve the target CV%. All thirteen analytes control levels (PCC1 & PCC2) failed to achieve the manufacturer’s recommended CV %. Discussion: The failure in achieving the target coefficient of variation (CV) for some analytes is attributed to instrument inaccurate calibration, variation or performance, sample handling/ processing, analytical techniques, environmental factors, reagent stability, interfering substances, quality control measures, and matrix effect. Address these factors through proper training of personnel, regular maintenance and calibration of instruments, stringent adherence to standard operating procedures, evaluation of reagent quality and robust quality control measures can help mitigate variability and improve the precision and repeatability of assay results. Conclusions: The performance of precision studies was average(i) Short-term precision – All analytes except one met CLIA target CV% and most met manufacturers set CV%. (ii) Long-term precision –Twenty out of twenty-six analytes’ levels met CLIA target CV% and all analytes failed to meet manufacturers target CV%.